Hitherto, in order to provide a rotational force to a device within a vacuum container whose inner space is made a vacuum, a rotary shaft for rotational force transmission may be provided so as to project from the inside of the vacuum container to the outside thereof.
In this case, in order to maintain a vacuum state by preventing atmospheric air from leaking from an annular space between the rotary shaft and a through hole, which is provided in the vacuum container for inserting the rotary shaft therethrough, into the vacuum container, a sealing device is mounted in the annular space (see e.g., PATENT LITERATURE 1).